private double CalculateExpense(Expense expense, int totalDays, int daysPresent)
 {
     if (expense.ExpenseType.Type == CategoryType.SplitEqual)
     {
         return expense.Amount / expense.ExpenseType.AffectedUsersIds.Count;
     }
     else
     {
         return (expense.Amount * daysPresent) / totalDays;
     }
 }
 public void Save(Expense entity)
 {
     this.session.Store(entity);
 }
 public void Remove(Expense entity)
 {
     throw new NotImplementedException();
 }